1. Field of the Invention
The invention described herein relates to communications systems, and more particularly to optical networks.
2. Related Art
Ethernet passive optical networks (EPON) are an emerging access network technology that provides a low-cost method of deploying optical access lines between a carrier's central office and a customer site. EPONs seek to bring to life the dream of a full-services access network (FSAN) that delivers converged data, video, and voice over a single optical access system. The carrier's central office typically contains a centralized controller device which is in optical communication with at least one subscriber device at the customer site. To communicate effectively with a subscriber device, the centralized controller device must be synchronized with the subscriber device.
For example, a section of the downstream channel can be framed for timing synchronization. A physical layer signal can be periodically transmitted on the framed portion of the downstream channel to broadcast a global time. This process creates problems, however, in that, the EPON has to rely on an exact transmission time. Further, such a process can be inefficient, as the signal has to be constantly transmitted, thereby wasting valuable bandwidth for transmitting time signals. Hence, what is needed is a method for expanding the MAC control layer in an EPON device to add additional control messaging to ensure efficient time synchronization and appropriate shared access of the media between a centralized controller device and subscriber devices in an EPON.